Recording medium and image-forming method employing the same

ABSTRACT

Provided is a recording medium comprising an ink-receiving layer provided on at least one face of a base material, wherein a surface of the ink-receiving has the maximum specular glossiness within a measurement angle range of from 20° to 60°.

This application is a continuation of application Ser. No. 08/518,171filed Aug. 23, 1995, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording medium having high glossincluding metallic luster, an image-forming method employing therecording medium, and a printed matter obtained by the image-formingmethod.

2. Related Background Art

Ink-jet recording is a recording method which conducts recording throughsteps of forming ink droplets, ejecting the ink droplets, and depositinga part or the whole of the ejected ink onto a recording medium such as apaper sheet or a plastic film coated with an ink-receiving layer. Theabove ink droplets are formed by various methods such as electrostaticattraction, mechanical vibration or displacement by a piezo-electricelement, pressure application by bubbling of ink by heating. The ink-jetrecording method is attracting attention because of less noisegeneration, and capability of high speed printing and multi-colorprinting.

The ink for ink-jet recording system is mainly composed of water in viewof safety, and recording characteristics. Frequently, a polyhydricalcohol is added to the ink to prevent clogging in a nozzle, and toimprove ejection stability.

The recording medium for the ink-jet recording includes various kinds ofpaper sheets, OHP films, glossy paper sheets, glossy films, cloth, etc.The method of feeding of the recording medium has developed, andautomatic sheet feeding is mainly employed in place of manual sheetfeeding.

The recording mediums conventionally employed include recording sheetsfor an overhead projector (hereinafter referred to as “OHP”) constitutedof a polyester film having thereon a hydrophilic film composed ofpolyvinyl alcohol of saponification degree of 70 mole percent to 90 molepercent as disclosed in Japanese Patent Application Laid-Open No.60-220750; recording paper sheets constituted of a base paper sheethaving a coating layer containing fine powdery silica and water-solublebinder like polyvinyl alcohol as disclosed in Japanese PatentPublication No. 3-26665; glossy paper sheets constituted of an opaquebase material like synthetic paper and having thereon a film mainlycomposed of a water-soluble resin; and so forth. Further, a cast-coatedpaper sheet for ink-jet recording having a coat layer formed by castingand mainly composed of silica and a binder is disclosed in JapanesePatent Application Laid-Open No. 63-265680.

As the results of improvements in performance of ink-jet recordingapparatus such as a higher printing rate, and multi-color printing, moreimprovements are required for the ink-jet recording medium. The requiredproperties for the ink-jet recording medium include: (1) higher inkabsorbency (larger absorption capacity, and shorter absorption time);(2) capability of giving higher optical density of the printed ink dotswithout blurring at the dot periphery; (3) capability of giving nearlycompletely circular dots with smoothness of the dot periphery; (4) lesschange of properties caused by change of temperature and humiditywithout causing curling of the recording medium; (5) no occurrence ofblocking; (6) capability of maintaining printed images stably for a longterm (especially under high temperature and high humidity); and (7)stability of the recording medium itself over a long term withoutdeterioration (especially under high temperature and high humidity).Various recording mediums are demanded with the increase of the printingspeed, increase of the image density, development of color printing, anddiversification of ink.

The ink-jet recording sheet disclosed in Japanese Patent Publication No.3-26665 has a mat-like surface appearance without gloss. The glossypaper sheet disclosed in Japanese Patent Publication No. 5-36237 doesnot exhibit sufficient gloss at non-printed portions although it allowsimage formation with high gloss and high density in comparison withconventional paper.

Conventional recording mediums have had a specular gloss which tends toincrease gradually with increase in specular glossiness when measuringit continuously with an angle of from 20° to 75°, and to reach themaximum at 75°. Therefore, the conventional recording mediums are notsatisfactory in dynamic representation of color owing to poor contrastof gloss at a non-printed area, and sufficient gloss of the recordingmedium can be perceived only when the medium is viewed at an obliqueangle since the specular glossiness has reached the maximum at 75°.

Conventional printed matters have had a specular gloss which tends toincrease gradually with increase in specular glossiness when measuringit continuously with an angle of from 20° to 75°, and to reach themaximum at 75°. Therefore, the conventional printed matters are notsatisfactory in dynamic representation of color owing to poor contrastof gloss at a non-printed area, and sufficient gloss of the printedmatters can be perceived only when the medium is viewed at an obliqueangle since the specular glossiness has reached the maximum at 75°.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a recording mediumwhich has sufficient gloss for decorativeness and is capable of givingdynamic color representation.

Another object of the present invention is to provide a printed matterof yellow, magenta, and cyan colors which has sufficient gloss fordecorativeness and is capable of giving dynamic color representation.

A further object of the present invention is to provide an ink-jetrecording medium having metallic luster, to provide a printed matterhaving metallic luster, and to provide a process for production thereof.

According to the present invention, there is provided a recording mediumcomprising an ink-receiving layer provided on at least one face of abase material, wherein a surface of receiving layer has the maximumspecular glossiness within a measurement angle range of from 20° to 60°.

According to the present invention, there is also privided a printedmatter printed with ink dots on a recording medium comprising anink-receiving layer provided on at least one face of a base material,and at least one of solid printed areas of yellow, magenta, and cyancolors has the maximum specular glossiness within a measurement anglerange of from 20° to 60°.

According to the present invention, there is further provided arecording medium comprising a metal foil, an ink-intercepting layerformed at least one face of the metal foil, and an ink-receiving layerformed on the ink-intercepting layer.

According to the present invention, there is still provided a recordingmedium comprising a film having an ink-intercepting effect,vapor-deposited metal on one face of the film, and an ink-receivinglayer provided on the reverse face of the film.

According to the present invention, there is still further provided animage-forming method which forms an image by ink-jet recording system onthe aforementioned recording medium.

According to the present invention, there is also still provided aprocess for the production of printed matter comprising forming aprinted matter having metallic luster by ink-jet recording system on theaforementioned recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a recording head of anink-jet recording apparatus.

FIG. 2 is a lateral cross-sectional view of a recording head of anink-jet recording apparatus.

FIG. 3 is a perspective view of a recording head constructed bymultiplication of the recording head shown in FIG. 1.

FIG. 4 is a perspective view of an ink-jet recording apparatus.

FIG. 5 is a conceptual graph showing dependence of the specularglossiness of a recording medium of the present invention on measurementangle.

FIG. 6 is a conceptual graph showing dependence of the specularglossiness of a conventional recording medium on measurement angle.

FIG. 7 is another conceptual graph showing dependence of the specularglossiness of a recording medium of the present invention on measurementangle.

FIG. 8 is another conceptual graph showing dependence of the specularglossiness of a conventional recording medium on measurement angle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has been found by the inventors of the present invention, duringtheir development work for a recording medium for ink-jet recordingsystem, that the aforementioned printed matter has excellentdecorativeness and achieves dynamic color saturation and hue expression,and the present invention has been completed based on the abovefindings.

The printed matter having excellent decorativeness and dynamic colorsaturation and hue expression herein means the one which has a basematerial, and an ink-receiving layer formed on at least one face of thebase material, where a solid printed area of at least one of yellow,magenta, and cyan colors of the print has the maximum specularglossiness within a measurement angle range of from 20° to 60°, and thespecular glossiness exceeds 100% at a measurement angle ranging from 20°to 75°.

In a case that the maximum specular glossiness can be obtained at anincident light angle of 60° or more, it cannot be observed visuallyunless it is viewed at an oblique angle. Also, in a case that thespecular glossiness is lower than 100% throughout the all measurementangle, the glossiness is felt to be insufficient as a whole similarly asconventional glossy paper sheets. Furthermore, the recording medium isobserved usually at a right angle rather than at an oblique angle.

The above-mentioned printed matter of the present invention hassufficient glossiness and excellent decorativeness, and capable ofexpressing dynamic color saturation and hues.

The present invention is described below in more detail by reference topreferred embodiments.

The base material employed in the present invention may be any material,provided that the recording medium or the printed matter has the abovephysical properties. The material includes paper such as pure paper,medium-quality paper, art paper, bond paper, regenerated paper, barytapaper, cast-coated paper, and corrugated fiberboard paper; films ofplastics such as polyethylene terephthalate, cellulose diacetate,cellulose triacetate, cellophane, celluloid, polycarbonates, polyimides,polyvinyl chlorides, polyvinylidene chlorides, polyacrylates,polyethylenes, and polypropylenes; wood boards; glass plates; cloth madefrom materials such as cotton, rayon, acrylics, silk, and polyesterfiber, and so forth. The surface of the base material may be smooth orrough, or transparent, translucent, or opaque. The base material may bea lamination of the two or more of the above mentioned materials.Naturally, the base material is not limited to the above materials.

The base material may have a metal film on the one or both facesthereof, or a mat layer, releasable adhesive layer, or the like on theface reverse to the printing face, or may be provided with an adhesivelayer on the printed face after printing.

The metal film may be a foil of gold, silver, copper, aluminium, or thelike, or a vapor deposition film of the above metal.

An ink-receiving layer is preferably formed on the metal film withinterposition of an ink-intercepting layer in order to maintain themetallic luster stably and perpetually for a long time. Without theink-intercepting layer, water or a dye contained in the ink tends toreact with the metal such as aluminium, or copper during a long term ofstorage of the printed matter to cause loss of metallic luster, orcorrosion of the metal foil.

Any of the metal face, the ink-intercepting layer, and the ink-receivinglayer may be colored. For example, when aluminium foil is used, theink-intercepting layer may be colored yellow to obtain a goldenrecording medium, or may be colored reddish brown to obtain acopper-colored recording medium.

If the ink-intercepting layer is colored, the coloration is preferablymade to be highly transparent so as not to impair the metallic luster.The coloration may be conducted in any method. Generally, it ispreferably colored with a dye.

The material for the ink-intercepting layer includes films of plasticssuch as polyethylene terephthalate, cellulose diacetate, cellulosetriacetate, cellophane, celluloid, polycarbonates, polyimides, polyvinylchlorides, polyvinylidene chlorides, polyacrylates, polyethylenes, andpolypropylenes; glass plates; and the like.

The metal film has preferably a thickness ranging from 1 Å to 20 μm.With the thickness of less than 1 Å, the metallic luster characteristicof the metal is not obtainable. With the thickness of more than 20 μm,the effect of the thickness is not obtainable.

Without using the metal film, the recording medium of the presentinvention can be obtained by incorporating a powdery metal into theink-receiving layer, by providing at least one powdery metal-containinglayer between the ink-receiving layer and the base material or on theface reverse to the ink-receiving layer, or by a like method.

The aforementioned powdery metal includes powder of metals such as gold,silver, copper, brass, aluminium, titanium, magnesium, beryllium,platinum, nickel, cobalt, chromium, palladium, and zinc; oxidationproducts thereof; alloys thereof, but is not limited thereto. A metalfilm having been separately formed and cut finely may be used in placeof the powdery metal.

The base material having the metal film may be fabricated as mentionedabove, provided that the objects of the present invention can beachieved.

Further in the present invention, by forming a fine rugged pattern onthe surface of the base material or the ink-receiving layer aninterference of the reflected light is caused and then an imagebrightened as rainbow can be produced.

Embossing the base material having convexities and concavities mentionedabove can make also an image brightened as rainbow three-dimensional.

The base material of the recording medium is selected from the abovematerials depending on the purpose of the recording, the use of theprinted image, adhesiveness to the composition applied thereon, andother conditions.

The material for the ink-receiving layer is not specially limited, andis not limited to those having solubility in or affinity to the aqueousink, or ink acceptability. The material includes synthetic resins suchas polyvinylpyrrolidones, polyvinyl alcohols, anion-modified polyvinylalcohols, cation-modified polyvinyl alcohols, polyurethanes,carboxymethylcelluloses, polyesters, polyacrylic acids (and estersthereof), hydroxyethylcelluloses, cation-modifiedhydroxyethylcelluloses, melamine resins, and modified materials thereof;and natural resins such as albumin, gelatin, casein, starch, cationicstarch, gum arabia, and sodium alginate, but is not limited thereto.These material may be used alone or in combination of two or morethereof.

Further, the ink-receiving layer may be made from a water-dispersibleresin, including polyvinyl acetates, ethylene-vinyl acetate copolymers,polystyrenes, styrene-(meth)acrylate ester copolymers, vinylacetate-(meth)acrylate copolymers, poly(meth)acrylamides,(meth)acrylamide type copolymers, styrene-isoprene copolymers,styrene-butadiene copolymers, ethylene-propylene copolymers, polyvinylethers, and the like, but the material is not limited thereto. Suchwater-soluble resins and the water-dispersible resins may be used incombination of two or more thereof.

Among these materials, polyvinyl alcohols, cation-modified polyvinylalcohols, acetal-modified polyvinyl alcohols, hydroxyethylcelluloses andpolyvinylpyrrolidones are preferred in particular from the viewpoints ofexcellent transparencies of an ink-receiving layer and printed portions.

In order to prevent image-bleeding with time of the ink-receiving layer,a cationic compound may be incorporated thereto. The cationic compoundmay be any compound which has a cationic moiety in the molecule.

The cationic compound includes monoalkylammonium chloride,dialkylammonium chloride, tetramethylammonium chloride,trimethylphenylammonium chloride; quaternary ammonium type cationicsurfactants such as ethylene oxide-added ammonium chloride; amine salttype cationic surfactants; and ampholytic surfactants of alkylbetainetype, imidazolynium betaine type, and alanine type.

The cationic compound further includes polymers and oligomers such ascation-modified polyacrylamide, copolymers of acrylamide with a cationicmonomer, polyallylamine, polyamine sulfone, polyvinylamine,polyethylenimine, polyamide-epichlorohydrin resins, polyvinylpyridiniumhalide, and the like.

The cationic compound further includes homopolymers of vinylpyrrolidonetype monomers and copolymers thereof with a usual monomer; homopolymersof vinyloxazolidone type monomers and copolymers thereof with a usualmonomer; and homopolymers of vinylimidazole type monomers and copolymersthereof with a usual monomer. The aforementioned usual monomer includesmethacrylates, acrylates, acrylonitrile, vinyl ethers, vinyl acetate,ethylene, styrene, and the like.

The above cationic compounds may be used alone or in combination of twoor more thereof, or a low molecular cationic compound and a highmolecular cationic compound may be used combinedly. In the presentinvention, the above cationic compound is not essential, but plays asupplemental role.

The ink-receiving layer may further contain a crosslinking agent such asmethylolated melamine, methylolated urea, methylolated hydroxypropyleneurea, isocyanates, and the like.

To obtain a suitable surface smoothness of the ink-receiving layer, afiller or additives may be used in such an amount that the object of thepresent invention is not hindered. The filler includes silica, alumina,aluminum silicate, calcium silicate, magnesium silicate, basic magnesiumcarbonate, talc, clay, mica, hydrotalcite, calcium carbonate, bariumcarbonate, titanium oxide, zinc oxide, plastic pigments such aspolyethylene, polystyrene, and polyacrylate, and glass beads, but is notlimited thereto.

The additives include surfactants, dye-fixing agents (water-proofingagents), antifoaming agents, antioxidants, fluorescent brighteners,UV-absorbing agents, dispersants, viscosity-controlling agents,pH-controlling agents, mildew-proofing agents, and plasticizers. Theseadditives are selected from known conventional compounds to meet theobjects.

The ink-receiving layer of the recording medium or the printed matter ofthe present invention is prepared as below. The mixture of theaforementioned components, optionally with other additives, is dissolvedor dispersed in water, an alcohol, a polyhydric alcohol, or anothersuitable organic solvent to prepare a coating liquid. The resultingcoating liquid is applied onto the surface of the base material by rollcoating, blade coating, air knife coating, gate roll coating, barcoating, size press coating, spray coating, gravure coating, curtaincoating, or the like method. Then the applied matter is dried by a hotair dryer, hot drum, or the like dryer to obtain a recording medium ofthe present invention.

An amount of the coating liquid to form the ink-receiving layer is in atotal amount ranging from 0.2 to 50 g/m², preferably from 1 to 30 g/m²in a dry base. Portions of the base material may be uncoated when thecoating amount is small. However, with the coating amount of less than0.2 g/m², the intended effects of the coating in coloring property isinsufficient, whereas with the coating amount of more than 50 g/m², therecording medium will curl remarkably, in particular, under lowtemperature and low humidity environment. The amount of coating in termsof thickness is preferably in the range of from 0.5 to 100 μm.

Any known ink may be used for the ink-jet recording system on therecording medium of the present invention described above. The recordingagent for the ink includes water-soluble dyes exemplified by directdyes, acid dyes, basic dyes, reactive dyes, and food colors, dispersedyes, and pigments. Any conventional ink-jet recording ink is usefulwithout limitation. A conventional ink contains the water-soluble dye,disperse dye, or the pigment at a content ranging from about 0.1% to 20%by weight. This range of the content is satisfactory in the ink used inthe present invention.

The solvent for the aqueous ink employed in the present invention iswater, or preferably a mixture of water with a water-soluble organicsolvent. The water-soluble organic solvent is preferably a polyhydricalcohol exhibiting the effect of prevention of ink drying.

The printing with the above-described ink on the above-describedrecording medium is conducted preferably by an ink-jet recording system.Any type of ink-jet recording system is useful which ejects ink througha nozzle effectively onto a recording medium. In particular, the ink-jetsystem, disclosed in Japanese Patent Application Laid-Open No. 54-59936,is effectively employed which ejects ink through a nozzle by action ofabrupt volume change of the ink caused by thermal energy.

An example of the ink-jet recording apparatus which is suitable forink-jet recording system of the present invention is explained byreference to the drawings. FIGS. 1, 2, and 3 illustrates an example ofthe construction of a head which is the essential part of the apparatus.

In these drawings, a head 13 is constructed by bonding a plate of glass,ceramics, or plastics having grooves 14 for ink flow with aheat-generating head 15 for thermal recording. (The heat-generating headis not limited to the thin film head shown in the drawings.) Theheat-generating head 15 is constituted of a protection layer 16 formedfrom silicon oxide or the like; aluminum electrodes 17-1, 17-2; aheat-generating resistance layer 18 made of nichrome or the like; aheat-accumulating layer 19; and a heat-radiating substrate plate 20 madeof alumina or the like.

The ink 21 fills an ejection orifice (fine nozzle) 22, and has ameniscus 23 formed by a pressure P.

On application of an electric signal information to the electrodes 17-1,17-2 of the head, the region denoted by a symbol “n” on theheat-generating head 15 generates heat abruptly to form bubbles in theink 21 on that region, the pressure of the bubble pushes out themeniscus 23 to eject the ink 21 from the orifice 22 in a shape ofdroplets 24. The ejected ink droplets travel toward a recording medium25.

FIG. 3 shows an external appearance of a multiple head integrating aplurality of heads shown in FIG. 1. The multiple head is formed bybonding a glass plate 27 having multiple grooves 26 with theheat-generating head 28 like the one shown in FIG. 1. FIG. 1 is across-sectional view of the head 13 along the ink flow path. FIG. 2 is across-sectional view along the line 2-2′ in FIG. 1.

FIG. 4 shows an example of the entire of the ink-jet recording apparatusequipped with the above-described head. In FIG. 4, a blade 61 as awiping member is held at one end of the blade by a blade-holding member,forming a fixed end in a shape of a cantilever. The blade 61 is placedat a position adjacent to the recording region of the recording head,and, in this example, is held so as to protrude to the moving path ofthe recording head. The cap 62 is placed at a home position adjacent tothe blade 61, and is constituted such that it moves in the directionperpendicular to the moving direction of the recording head to come intocontact with the ejection nozzle face to cap the nozzle. An inkabsorbent 63 is placed at a position adjacent to the blade 61, and isheld so as to protrude to the moving path of the recording head in amanner similar to that of the blade 61. The blade 61, the cap 62, andthe absorbent 63 constitute an ejection recovery device 64. The blade61, and the absorbent 63 serve to remove off water, dust, etc. from theface of the ink ejection nozzle.

A recording head 65 has an energy-generating means for the ejection, andconducts recording by ejecting the ink onto a recording medium opposingto the ejection nozzle face. A carriage 66 is provided for supportingand moving the recording head 65. The carriage 66 is engaged slidablywith a guide rod 67. A portion of the carriage 66 is connected (notshown in the drawing) to a belt 69 driven by a motor 68, so that thecarriage 66 is movable along the guide rod 67 to the recording region ofthe recording head 65 and the adjacent region thereto.

A paper delivery device 51 for delivery of a recording medium and apaper delivery roller 52 driven by a motor (not shown in the drawing)delivers a recording medium to the position facing to the ejectionnozzle face of the recording head, and the recording medium is deliveredwith the progress of the recording to a paper discharge device providedwith paper-discharging rollers 53.

In the above constitution, when the recording head 65 returns to thehome position on completion of recording, the cap 62 of theejection-recovery device 64 is positioned out of the moving path of therecording head 65, and the blade 61 is allowed to protrude to the movingpath. Thereby, the ejecting nozzle face of the recording head 65 iswiped. To cap the ejection face of the recording head 65, the cap 62protrudes toward the moving path of the recording head to come intocontact with the ejection nozzle face.

When the recording head 65 is made to move from the home position to therecord-starting position, the cap 62 and the blade 61 are at the sameposition as in the above-mentioned wiping step, so that the ejectionnozzle face of the recording head 65 is wiped also in this movement.

The recording head is moved to the home position not only at thecompletion of the recording and at the time of ejection recovery, but isalso moved at a predetermined intervals during recording from therecording region. The nozzle is wiped by such movement.

The present invention is described in more detail by reference toexamples. In the examples, the terms “part” and “%” are based on weightunless otherwise mentioned.

Example 1

A gold foil “Sample Daicho No. 56, produced by Murata Gold Foil K.K.”which has the maximum specular glossiness at the incident angle of about45° was employed as the base material. On this base material, an aqueous10% solution of polyvinyl alcohol (trade name: PVA-217, produced byKuraray Co., Ltd.) was applied by wire bar coating so as to obtain a drythickness of 10 μm as the ink-receiving layer, and the obtained matterwas dried at 120° C. for 3 minutes to prepare a recording medium of thepresent invention. On the resulting recording medium, printing wasconducted by means of a color bubble jet printer (trade name: BJC-600,manufactured by Canon K.K.).

Examples 2 to 12 and Comparative Examples 1 to 8

Recording mediums were prepared in the same manner as in Example 1except for the conditions shown in Table 1.

The printed matters obtained in the above Examples and ComparativeExamples were evaluated as below.

TABLE 1 Base material Ink-receiving layer material Example 2 SampleDaicho No. 03 Same as in Example 1 (Murata Gold Foil K.K.) 3 SampleDaicho No. 75 Same as in Example 1 (Murata Gold Foil K.K.) 4 SampleDaicho No. 101 Same as in Example 1 (Murata Gold Foil K.K.) 5 SampleDaicho No. 109 Same as in Example 1 (Murata Gold Foil K.K.) 6 3DILLUSION PAPER Same as in Example 1 (AD STICKER) 7 Same as in Example 1Polyvinylacetal (KW-1. Sekisui Chem. Co.) 8 Same as in Example 1Hydroxyethylcellulose (Al-15, Fuji Chemical K.K.) 9 Same as in Example 1Cation-modified polyvinyl alcohol (CM-318, Kuraray Co.) 10 Bone-whitecolored PET film Mixture of 100 parts of (Bone-White Lumirror 100E20Polyvinyl alcohol (PVA-217, Kuraray) and 10 parts of Toray Ind. Inc.,100 μm thick) Rainblow Piece (No. 608G, Kurachi K.K.) 11 Coated paperSame as in Example 10 (LC-201, Canon K.K.) 12 PPC paper Same as inExample 10 (TY PE6000, Ricoh Co.) Comparative Example 1 White PET film(100 μm thick, Same as in Example 1 White Lumirror, Toray Ind.) 2 Sameas in Example 10 Same as in Example 1 3 Same as in Example 1Polyethylene oxide (EP-15, Daiichi Kogyo Seiyaku K.K.) 4 Glossy paper(NS-101, Canon K.K.) 5 Colored paper (BIO TOP COLOR, Itoya Dep. PaperK.K.) 6 Same as in Example 10 Mixture of 100 parts of polyvinyl alcohol(PVA-217, Kuraray) and 10 parts of silica particles (Silicia 470, FujiSilicia Chemical K.K. average particle size 12 μm) 7 Same as in Example11 Same as in Comparative Example 6 8 Same as in Example 12 Same as inComparative Example 6

[Items and Methods of Evaluation]

(1) Specular Glossiness at a Non-printed Area

Using a digital angle variation glossimeter (UGV-5D, manufactured bySuga Tester K.K.) specular glossiness at a non-printed area of arecording medium was measured at measurement angles of 20°, 45°, 60°,and 75° according to JIS-Z-8741. The average value of five measuredvolues was taken the specular glossiness at for each measurement angle.

The recording medium having the maximum specular glossiness at the angleother than 75° was evaluated to be “good”, and the one having themaximum specular glossiness at 75° was evaluated to be “poor”.

(2) Specular Glossiness at a Printed Area

Similar to (1), specular glossinesses at solid printed areas of yellow,magenta and cyan colors were measured each at measuring angles of 20°,45°, 60° and 75° according to JIS-Z-8741. The average values of eachfive measured values were taken for the specular glossiness at eachmeasuring angles. The maximum specular glossiness and its measuringangle of each color are shown in Table 2.

(3) Decorativeness

The decorativeness was evaluated of the non-printed area and of theprinted area. The recording medium having higher decorativeness than PPCpaper was evaluated to be “good”, and the one having decorativeness notsignificantly improved was evaluated to be “poor”.

FIG. 5 and FIG. 6 respectively show dependence of the specularglossiness of the recording medium of the present invention and that ofa conventional one conceptually.

The results of the evaluation are shown in Table 2.

TABLE 2 Specular Glossiness at a non-printed area Decorativeness 20° 45°60° 75° Evaluation Non-printed area Printed area Example 1 54.8 172.2135.4 117.5 Good Good Good 2 150.2 >370 304.6 171.7 Good Good Good 3170.3 356.8 289.9 180.5 Good Good Good 4 150.5 320.9 256.5 138.6 GoodGood Good 5 120.7 333.5 275.6 171.4 Good Good Good 6 85.2 220.3 142.8110.2 Good Good Good 7 55.6 174.5 132.5 117.3 Good Good Good 8 53.8173.3 136.5 121.5 Good Good Good 9 54.1 170.3 128.5 121.5 Good Good Good10 79.2 289.5 204.6 89.4 Good Good Good 11 44.2 172.3 123.1 78.6 GoodGood Good 12 32.8 64.2 87.5 42.9 Good Good Good Comparative Example 176.6 88.1 91.7 99.6 Poor Poor Poor 2 4.9 31.8 39.6 67.2 Poor Poor Poor 342.6 54.6 70.4 78.6 Poor Poor Poor 4 22.1 49.4 53.8 80.3 Poor Poor Poor5 0.4 3.2 3.4 6.1 Poor Poor Poor 6 74.5 85.3 90.8 96.6 Poor Poor Poor 73.4 6.5 10.3 19.2 Poor Poor Poor 8 0.7 3.6 5.6 10.4 Poor Poor PoorMaximum specular glossiness at a printed area Cyan Magent Yellow ExampleSpecular Angle Specular Angle Specular Angle No. glossiness (°)glossiness (°) glossiness (°) Example 1 153.3 45 147.2 45 162.4 452 >370 45 356.2 45 >370 45 3 305.8 45 312.2 45 333.4 45 4 286.5 45 278.445 311.7 45 5 308.5 45 302.1 60 300.8 60 6 189.6 45 180.0 45 204.2 45 7162.7 45 152.9 45 161.0 45 8 145.6 45 152.8 45 158.4 45 9 150.0 45 144.445 158.9 45 10 260.2 45 256.3 45 270.1 45 11 145.6 45 150.8 45 157.6 4512 78.9 60 77.7 45 80.2 60 Comparative Example 1 82.2 75 80.7 75 85.4 752 46.0 75 50.2 75 54.0 75 3 54.2 75 50.1 75 58.6 75 4 61.5 75 64.0 7563.7 75 5 4.3 75 5.2 75 3.9 75 6 76.9 75 71.5 75 77.8 75 7 12.3 75 14.275 10.5 75 8 5.2 75 6.0 75 6.1 75

Example 13

A gold foil “Sample Daicho 506, produced by Murata Gold Foil Co.” whichhas the maximum specular glossiness at the incident angle of around 45°was employed as the base material. On this base material, an aqueous 10%solution of polyvinyl alcohol (trade name: PVA-217, produced by KurarayCo., Ltd.) was applied by wire bar coating so as to obtain a drythickness of 10 μm as the ink-receiving layer, and the obtained matterwas dried at 120° C. for 3 minutes to prepare a recording medium of thepresent invention. On the resulting recording medium, solid printing wasconducted for each of cyan, magenta, and yellow colors at a printingmode for an OHP sheet by means of a color bubble jet printer (tradename: BJC-600, manufactured by Canon K.K.) to obtain a printed matter ofthe present invention.

Examples 14 to 26 and Comparative Examples 9 to 17

Printed matters were prepared in the same manner as in Example 13 exceptfor the conditions shown in Table 3.

TABLE 3 Base material Ink-receiving layer material Example 14 SampleDaicho No. 84 Same as in Example 13 (Murata Gold Foil K.K.) 15 SampleDaicho No. 103 Same as in Example 13 (Murata Gold Foil K.K.) 16 SampleDaicho No. 117 Same as in Example 13 (Murata Gold Foil K.K.) 17 SampleDaicho No. 155 Same as in Example 13 (Murata Gold Foil K.K.) 18 SampleDaicho No. 204 Same as in Example 13 (Murata Gold Foil K.K.) 19Infinitone Film Same as in Example 13 (Murata Gold Foil K.K.) 20Aluminum vapor-deposited film Same as in Example 13 (Metalumy, TorayInd., 100 μm thick) 21 Same as in Example 13 Polyvinylacetal (KW-1.Sekisui Chem. Co.) 22 Same as in Example 13 Hydroxyethylcellulose(A1-15, Fuji Chemical K.K.) 23 Same as in Example 13 Cation-modifiedpolyvinyl alcohol (CM-318, Kuraray Co.) 24 White PET film (WhiteLumirror, Mixture of 100 parts of polyvinyl alcohol of Toray Ind. Inc.,100 um thick) Example 23 and 10 parts of copper powder 25 Glossy paperSame as in Example 24 (NS-101, Canon K.K.) 26 PPC paper Same as inExample 24 (#4024, Xerox Co.) Comparative Example  9 Same as in Example24 Same as in Example 13 10 Bone-white colored PET film Same as inExample 13 (Bone-White Lumirror 100E20 Toray Ind. Inc., 100 μm thick) 11Glossy paper (NS-101, Canon K.K.) 12 Colored paper (BIO TOP COLOR, ItoyaDep. Paper K.K.) 13 PPC paper (#4024, Xerox Co.) 14 Same as in Example24 Mixture of 100 parts of cation-modified polyvinyl alcohol (CM-318,Kuraray Co.) and 10 parts of fine silica particles (Silicia 470, Fujisilicia Chemical K.K., average particle size: 12 μm) 15 Same as inExample 25 Same as in Comparative Example 15 16 Same as in Example 26Same as in Comparative Example 15

The printed matters obtained in the above Examples and ComparativeExamples were evaluated as below.

[Items and Methods of Evaluation]

(1) Specular Glossiness

Using a digital angle variation glossmeter (UGV-5D, manufactured by SugaTester K.K.) specular glossiness at solid printed areas of each ofyellow, magenta, and cyan colors was measured at measurement angles of20°, 45°, 60°, and 75° according to JIS-Z-8741. The average value of thefive measured values was taken for the specular glossiness at eachmeasurement angle.

The recording medium having the maximum specular glossiness at the angleother than 75° for at least one of the yellow, magenta, and cyan colorswas evaluated to be “good”, and the one having the maximum specularglossiness at 75° for all of the three colors was evaluated to be“poor”.

(2) Achievement Degree of Specular Glossiness

The sample in which the maximum specular glossiness appeared at an angleother than 75° for each of the colors of yellow, magenta, and cyan, andthe maximum values were not less than 100% was evaluated as “A”. Thesample in which the maximum specular glossiness appeared at an angleother than 75° for two of the three colors of yellow, magenta, and cyan,and the maximum values for the two colors were not less than 100% wasevaluated as “B”. The sample in which the maximum of the specularglossiness appeared at an angle other than 75° for one of the threecolors of yellow, magenta, and cyan, and the maximum value for the onecolor was not less than 100% was evaluated as “C”. The sample in whichthe maximum specular glossiness appeared at an angle other than 75° forone of the three colors of yellow, magenta, and cyan, and the maximumvalue for the one color was less than 100% was evaluated as “D”. Thesample in which the maximum specular glossiness appeared at 75° for allof the three colors was evaluated as “E”.

(3) Decorativeness

The recording medium having higher decorativeness than PPC paper wasevaluated to be “good”, and the one having decorativeness notsignificantly improved was evaluated to be “poor”.

FIG. 7 and FIG. 8 respectively show dependence of the specularglossiness of the printed matter of the present invention and that of aconventional one conceptually.

The results of the evaluation are shown in Table 4 and Table 5.

TABLE 4 Specular Glossiness of Printed Area Cyan Magenta Yellow 20° 45°60° 75° 20° 45° 60° 75° 20° 45° 60° 75° Example 13 39.4 90.8 89.4 102.534.8 84.8 86.4 94.0 40.5 118.2 107.0 97.1 14 42.5 98.4 80.3 78.4 40.593.3 87.9 80.3 38.3 109.8 98.6 90.3 15 154.5 209.8 180.6 130.6 136.7208.5 150.2 100.7 278.9 333.4 264.4 167.4 16 60.9 146.7 120.9 102.2 56.7149.0 109.8 100.7 100.0 277.8 187.7 120.2 17 40.6 87.6 92.7 100.7 40.787.7 84.2 98.8 45,7 129.2 102.9 92.1 18 229.1 293.8 183.4 119.2 151.7203.8 149.5 109.7 >370 >370 354.9 171.1 19 54.2 88.8 86.0 89.9 52.8 82.685.5 88.9 60.0 93.2 90.3 89.4 20 347.4 352.8 199.0 112.3 215.8 237.1150.7 103.3 >370 >370 >370 179.2 21 42.5 98.3 90.8 99.2 35.7 88.8 82.292.2 50.9 130.2 111.9 98.2 22 33.4 89.9 82.2 98.3 30.3 89.3 81.1 92.946.4 122.4 108.8 99.1 23 46.4 109.2 91.1 96.2 42.3 92.2 82.4 96.2 52.6143.3 121.1 108.8 24 87.6 96.2 80.8 75.4 79.8 105.3 89.9 76.3 81.5 143.7112.3 88.4 25 43.4 78.3 70.4 66.3 44.5 88.1 80.0 67.7 50.4 102.3 89.977.4 26 24.5 44.3 56.4 47.6 22.2 36.5 50.3 60.3 19.9 56.4 50.4 44.8Comparative Example  9 60.3 87.1 89.2 97.6 61.9 83.3 87.0 94.8 56.1 84.186.2 94.0 10 40.1 82.8 76.5 96.8 43.8 79.2 83.3 94.5 38.4 79.6 82.2 94.411 10.9 38.7 43.4 69.2 12.8 40.6 48.8 78.3 12.8 40.9 48.5 74.4 12 0.43.6 4.0 4.2 1.0 3.0 3.6 4.0 1.3 2.2 2.8 4.0 13 0.2 2.8 3.2 3.3 0.8 1.82.2 3.5 1.2 2.1 2.7 3.7 14 31.4 70.2 72.2 86.2 30.5 67.7 71.1 81.2 34.069.6 75.5 89.5 15 12.2 40.1 48.3 71.3 15.2 43.6 47.3 75.6 14.3 36.8 47.876.3 16 3.6 7.3 10.3 12.1 3.0 6.3 9.4 11.1 4.6 8.3 12.8 16.3

TABLE 5 Specular glossiness Decorativeness Degree of of Evaluationachievement printed matter Example 13 Good C Good 14 Good C Good 15 GoodA Good 16 Good A Good 17 Good C Good 18 Good A Good 19 Good D Good 20Good A Good 21 Good C Good 22 Good C Good 23 Good B Good 24 Good B Good25 Good C Good 26 Good D Good Comparative Example  9 Poor E Poor 10 PoorE Poor 11 Poor E Poor 12 Poor E Poor 13 Poor E Poor 14 Poor E Poor 15Poor E Poor 16 Poor E Poor

Example 27

An aqueous 9% solution of a cation-modified polyvinyl alcohol (tradename: CM-318, produced by Kuraray Co., Ltd., saponification degree:about 89 mole percent, polymerization degree: about 1700,cation-modification degree: about 2 mole percent) was applied on analuminum vapor-deposited film (trade name: Metalmee 100TS, produced byToray Industries Inc., thickness 100 μm) on the face reverse to thealuminum deposition face so as to obtain the dry thickness of thecoating of 10 μm, and the obtained matter was dried at 120° C. for 3minutes to form an ink-receiving layer, thus completing a recordingmedium of the present invention.

On the recording medium, a color image was formed with the ink havingthe composition below by means of an ink-jet recording apparatus whichejects ink by bubbling of the ink by thermal energy under the recordingconditions shown below.

C.I. Direct Black 19 3 parts Glycerin 6 parts Ethylene glycol 5 partsUrea 5 parts Isopropyl alcohol 3 parts Water 78 parts

The surface tension of this ink was about 45 dyn/cm.

Ink Composition (Yellow, Cyan, and Magenta)

Dye 4 parts Glycerin 7 parts Thiodiglycol 7 parts Urea 7 parts Acetyleneglycol 1.5 parts Water 73.5 parts

Dyes

Yellow: C.I. Direct Yellow 86 Magenta: C.I. Acid Red 23 Cyan: C.I.Direct Blue 199

Recording Conditions

Ejection frequency: 4 kHz Volume of droplet: 45 pl Recording density:360 DPI Maximum ink application of single color: 8 nl/mm²

Example 28

A recording medium was prepared in the same manner as in Example 27except that the aluminum vapor-deposited film was replaced by acommercial 15 μm-thick aluminum cooking foil on which a 75 μm-thickcolorless transparent PET film had been laminated by hot-pressing at theglossier face side thereof. Thereon, a color image was formed by ink-jetrecording in the same manner as in Example 27.

Example 29

A recording medium was prepared in the same manner as in Example 27except that the aluminum vapor-deposited film was replaced by acommercial 15 μm-thick aluminum cooking foil on which a 75 μm-thickyellow PET film had been laminated by hot pressing at the glossier faceside thereof. Thereon, a color image was formed by ink-jet recording inthe same manner as in Example 27.

Example 30

A recording medium was prepared in the same manner as in Example 27except that the aluminum vapor-deposited film was replaced by acommercial 15 μm-thick aluminum cooking foil on which a 75 μm-thickreddish brown PET film had been laminated by hot-pressing at theglossier face side thereof. Thereon, a color image was formed by ink-jetrecording in the same manner as in Example 27.

Example 31

A recording medium was prepared in the same manner as in Example 27except that the aluminum vapor-deposited film was replaced by acommercial 30 μm-thick copper foil on which a 75 μm-thick colorlesstransparent PET film had been laminated by hot-melting at the glossierface side thereof. Thereon, a color image was formed by ink-jetrecording in the same manner as in Example 27.

Example 32

A recording medium was prepared in the same manner as in Example 27except that the aluminum vapor-deposited film was replaced by acommercial 15 μm-thick aluminum cooking foil on which a 75 μm-thickcolorless transparent PET film having a white flower pattern printedthereon had been laminated by hot-pressing at the glossier face sidethereof. Thereon, a color image was formed by ink-jet recording in thesame manner as in Example 27.

Example 33

A recording medium was prepared in the same manner as in Example 27except that the ink-receiving layer is formed by application of anaqueous solution of a mixture of 100 parts of a cation-modifiedpolyvinyl alcohol (trade name: CM-318, produced by Kuraray Co., Ltd.,saponification degree: about 89 mole percent, polymerization degree:about 1700, cation-modification degree: about 2 mole percent) and 20parts in the terms of solid of an aqueous emulsion of an acrylate estertype copolymer (trade name: Movinyl 742N, produced by Hoechst SynthesisCo., solid content: 46%, MFT: 50° C.). Thereon, a color image was formedby ink-jet recording in the same manner as in Example 27.

Example 34

A recording medium was prepared and a color image was formed in the samemanner as in Example 27 except that the ink-receiving layer was formedfrom a polyvinyl acetal (trade name: KW-1, produced by Sekisui ChemicalCo, Ltd.).

Example 35

A recording medium was prepared and a color image was formed in the samemanner as in Example 32 except that the ink-receiving layer was formedfrom a polyvinyl acetal (trade name: KW-1, produced by Sekisui ChemicalCo, Ltd.).

Example 36

A recording medium was prepared and a color image was formed in the samemanner as in Example 27 except that the ink-receiving layer was formedfrom a polyvinyl alcohol (trade name: PVA-217, produced by Kuraray Co,Ltd.).

Example 37

A recording medium was prepared and a color image was formed in the samemanner as in Example 32 except that the ink-receiving layer was formedfrom a polyvinyl alcohol (trade name: PVA-217, produced by Kuraray Co,Ltd.).

Example 38

A recording medium was prepared and a color image was formed in the samemanner as in Example 27 except that the ink-receiving layer was formedfrom hydroxyethylcellulose (trade name: AL-15, produced by Fuji ChemicalK.K.).

Example 39

A recording medium was prepared and a color image was formed in the samemanner as in Example 32 except that the ink-receiving layer was formedfrom hydroxyethylcellulose (trade name: AL-15, produced by Fuji ChemicalK.K.).

Example 40

A recording medium was prepared and color image was formed in the samemanner as in Example 33 except that the surface of the hot press-bondedfilm was treated for oxidation.

[Evaluation Items]

(1) Metallic Luster

The one having metallic luster is shown by the term “Lustered”, and theone having no metallic luster is shown by the term “None” in Table 6.

(2) Kind of Metallic Luster

The color of the metallic luster was observed.

(3) Metallic Luster Preservability-1

Printing was conducted under room conditions, and the printed matter wasstored at high temperature and high humidity environment of 45° C./95%for 4 weeks. Then the printed matter was evaluated for metallic lusterpreservability. The one exhibiting no change of the metallic luster wasevaluated to be “good”, the one exhibiting observable deterioration ofthe metallic luster was evaluated to be “fair”, and the one having nometallic luster was evaluated to be “poor”.

(4) Metallic Luster Preservability-2

Printing was conducted under room conditions, and the printed matter wasstored at high temperature and high humidity environment of 30° C./80%for 4 weeks. Then the printed matter was evaluated for metallic lusterpreservability. The one exhibiting no change of the metallic luster wasevaluated to be “good”, the one exhibiting observable deterioration ofthe metallic luster was evaluated to be “fair”, and the one having nometallic luster was evaluated to be “poor”.

(5) Ink Fixing Properties

The printed matter prepared with black ink, and full dots ofcombinations of two colors of yellow, cyan, and magenta was leftstanding for 2 minutes after recording. Then the paper was superposed onthe printed areas, and the superposed matter was rubbed at a pressure of4 kg/cm². Then the paper was separated from the printed matter. The onewhich showed ink transfer to impair the printed image remarkably wasevaluated to be “poor”, the one which showed slight ink transfer toimpair the printed image slightly was evaluated to be “fair”, and theone which showed no ink transfer and no damage of the printed image wasevaluated to be “good”.

The evaluation results are shown collectively in Table 6.

TABLE 6 Maximum specular glossiness at a printed area Ex- Cyan MagentaYellow ample Specular Angle Specular Angle Specular Angle No. glossiness(°) glossiness (°) glossiness (°) 27 >370 20 360.2 45 >370 20 28 298.645 280.0 45 308.4 45 29 276.3 45 272.3 60 291.4 45 30 216.4 45 220.0 45230.7 45 31 222.6 60 218.7 60 226.4 45 32 306.4 45 291.5 60 330.6 45 33353.4 45 333.3 45 >370 20 34 >370 20 345.2 45 >370 20 35 311.0 45 307.245 321.3 45 36 >370 20 343.2 45 >370 20 37 302.1 45 294.7 45 312.4 45 38358.3 45 341.3 45 >370 20 39 298.6 45 291.8 45 305.6 60 40 248.2 45240.3 45 265.1 45 Metallic luster Ink Example Lustered Preserv- Preserv-fixing No. or not Color ability-1 ability-2 properties 27 LusteredSilver Good Good Fair 28 Lustered Silver Fair Good Fair 29 Lustered GoldFair Good Fair 30 Lustered Copper Fair Good Fair 31 Lustered Copper GoodGood Fair 32 Lustered Silver Fair Good Fair 33 Lustered Silver Fair GoodGood 34 Lustered Silver Fair Good Good 35 Lustered Silver Fair Good Good36 Lustered Silver Fair Good Good 37 Lustered Silver Fair Good Fair 38Lustered Silver Fair Good Fair 39 Lustered Silver Fair Good Fair 40Lustered Silver Good Good Good

The ink-jet recording medium of the present invention gives high imagequality which could not be achieved by conventional recording mediums.The ink-jet recording medium of the present invention exhibits higherglossiness when viewed from the front thereof unlike conventional glossyrecording medium, thereby giving high decorativeness, and enablesdynamic color representation.

The recording medium of the present invention gives desirable printedmatter without much labor, unlike conventional recording medium. Theprinted matter of the present invention gives high image quality whichcould not be achieved by conventional recording mediums. Further, theprinted matter of the present invention exhibits higher glossiness whenviewed from the front thereof unlike conventional glossy recordingmedium, thereby giving high decorativeness, and enables dynamic colorrepresentation.

The present invention gives also an ink-jet recording medium havingmetallic luster which is retained perpetually even under severeconditions of high temperature and high humidity.

What is claimed is:
 1. A recording medium comprising a base materialhaving a metal film thereon and having a surface with an embossedpattern which causes interference with reflected light on a printingface of the medium, a transparent ink-intercepting layer provided on themetal film of the base material and a transparent ink-receiving layerprovided on the ink-intercepting layer, wherein the ink-interceptinglayer is one or more films selected from polyolefin films and polyesterfilms, and wherein the ink-receiving layer comprises a water-solubleresin or a water-dispersible resin, and a surface of the ink-receivinglayer has a maximum specular glossiness within a measurement angle rangeof from 20° to 60° and the maximum value of the specular glossiness isnot less than 100%.
 2. The recording medium according to claim 1,wherein the specular glossiness exceeds 100% within a measurement anglerange of from 20° to 75°.
 3. The recording medium according to claim 1,wherein the metal film is a vapor-deposited metal layer.
 4. Therecording medium according to claim 3, wherein at least one of theink-intercepting layer and the ink-receiving layer is colored.
 5. Therecording medium according to claim 1, wherein at least one of the metalfilm, the ink-intercepting layer, and the ink-receiving layer iscolored.
 6. The recording medium according to claim 1, wherein the metalfilm is selected from gold foil, silver foil, copper foil, and aluminumfoil.
 7. The recording medium according to claim 1, wherein a metalcorrosion preventing film is provided on the face of the ink-receivinglayer reverse to the recording face.
 8. The recording medium accordingto claim 1, wherein the recording medium has a total thickness of notlarger than 500 μm.
 9. An image-forming method, comprising the step offorming an image with an ink and an ink-jet recording apparatus on therecording medium set forth in claim
 1. 10. The image-forming methodaccording to claim 9, wherein the ink comprises water and awater-soluble organic solvent.
 11. The image-forming method according toclaim 9, wherein the ink comprises a cyan ink, a magenta ink, a yellowink, and a black ink.
 12. The image-forming method according to claim11, wherein the black ink has a higher surface tension than the cyan,magenta, and yellow inks.
 13. The image-forming method according toclaim 9, wherein the ink-jet recording apparatus ejects ink by action ofthermal energy applied to the ink.
 14. A process for producing a printedmatter, comprising forming an image with an ink-jet recording apparatuson the recording medium set forth in claim 1 to obtain a printed matterhaving metallic luster.
 15. A printed matter in which an image is formedwith ink dots on the recording medium set forth in claim
 1. 16. Therecording medium according to claim 1, wherein the water-soluble resinis a resin selected from the group consisting of polyvinyl alcohol,cation-modified polyvinyl alcohol, acetal-modified polyvinyl alcohol,hydroxyethyl cellulose and polyvinylpyrrolidone.
 17. The recordingmedium according to claim 1, wherein the ink-receiving layer furthercomprises a cationic compound.
 18. The recording medium according toclaim 17, wherein the cationic compound is a material selected from thegroup consisting of monoalkylammonium chloride, dialkylammoniumchloride, tetramethylammonium chloride, trimethylphenylammoniumchloride, quaternary ammonium type cationic surfactant, amine salt typecationic surfactant and ampholytic surfactant.
 19. The recording mediumaccording to claim 17, wherein the cationic compound is a materialselected from the group consisting of cation-modified polyacrylamide,copolymer of acrylamide with a cationic monomer, polyallylamine,polyamine sulfone, polyvinylamine, polyethyleneimine,polyamide-epichlorohydrin resin and polyvinylpyridinium halide.
 20. Therecording medium according to claim 1, wherein the metal film has athickness of from 1 Å to 20 μm.